• Title, Summary, Keyword: thermoluminescence (TL)

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Physical Methods for the Identification of Irradiated Food

  • Yang, Jae-Seung;Lee, Hae-Jung
    • Preventive Nutrition and Food Science
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    • v.3 no.2
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    • pp.203-209
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    • 1998
  • The development of methods for the identification of irradiated foods helps enforce national and international regulations on labelling to ensure the consumer's free choice to buy irradiated or unirradiated foods. and the availabilityof such methods may assist the promotion of international trade in irradiated food products and help prevent abuse of the technology. A number of approaches to determine the physical , chemical, microbiological and biological changes that occur in foods treated with ionizing radiation have been studied. However no single method is universally applicable. Among physical measurements, the leading methods of indentification are electron spin resonance (ESR) spectroscopy and thermoluminescence(TL). ESR is an established non-destructive method for the analysis of free radicals from their traps and TL is the emission of light from irradiated mineral extracts by heating. Viscosity of carbohydrate polymers by causing chain breaks by irradiation, measuring the impedance of potatoes and detection of gases produced radiolytically are promising techniques for identification purposes. Irradiated water-containing foods show significant supercooling when monitored with a differential scanning calorimeter (DSC), which can be applied to identifying irradiated ones.

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Thermoluminescence Dating of Pottery Shards by Subtraction Method (Subtraction 방법을 이용한 TL 연대측정법에 의한 토기 시편의 절대연대 결정)

  • Shin, Hyun-Sang;Lee, Chang-Woo;Nam, Young-Mee;Jee, Kwang-Yong;Park, Byung-Bin
    • Analytical Science and Technology
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    • v.13 no.4
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    • pp.403-411
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    • 2000
  • This study described a method of thermoluminescence dating of pottery shards using subtraction method. TL measurement was achieved using two different types of samples prepared by quartz inclusion method and fine-grain technique. Fine grains (size range: $5-10{\mu}m$) were separated by suspending grounded pottery samples into acetone solution and sedimentation quantitatively. In quartz inclusion method quartz grains in the size range of 90 to $125{\mu}m$ diameter were obtained by extracting the quartz crystals embed in the pottery shards and etching them with 1.0 M HF solutions. The archaeological dose of both the quartz and fine grains was determined from the dose calibration curves obtained from sequential irradiation of $^{137}Cs$ gamma and $^{241}Am$ alpha source to the samples and TL measurement of natural samples, in which the alpha dose of 4.60 Gy for the Packjae pottery was obtained using subtraction method. Annual alpha dose rates ($3.05{\pm}0.11$ mGy/yr.) were determined by the analysis of U, Th contents in the pottery shards and evaluation of the values with Bell's equation. Dividing the alpha dose accumulated in the pottery shards by the annual alpha dose rate, we found age of approximately $1508{\pm}80$ years B.P. (AD. ca. 492 yr.) for the Packjae pottery. It matches well with the archeological age estimate (middle of 5th century) within 10 percent uncertainty and thereby conforms the age of the pottery sample.

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Photostimulated Luminescence-Thermoluminescence Application to Detection of Irradiated White Ginseng Powder (방사선 조사 백삼분말의 PSL-TL 다중검지법)

  • Chung, Hyung-Wook;Delincee, Henry;Kwon, Joong-Ho
    • Korean Journal of Food Science and Technology
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    • v.32 no.2
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    • pp.265-270
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    • 2000
  • White ginseng powder, permitted to be irradiated in Korea for the purpose of microbial decontamination, was treated with electron beam at doses of $0{\sim}15\;kGy$ for a detection trial whether it is irradiated or not by measuring photostimulated luminescence for whole samples first and then (TL) for the mineral adhering to the samples. PSL values were less than threshold value (700, $T_{1}$) and were negative for nonirradiated samples but more than 5000 $(T_2)$ and were positive for irradiated ones. After PSL measurement mineral was separated from the whole samples using density separation. Mineral of nonirradiated samples was characterized by glow curves which have low intensity and were situated at the high temperature region (about $300^{\circ}C$) by the low level of natural radioactivity. Glow curves of minerals for all irradiated samples were observed at about $200^{\circ}C$. TL ratio by normalization was 0.01 for nonirradiated sample and more than 0.78 for irradiated samples, and it was possible to detect whether white ginseng powders were irradiated or not.

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Optical dating of Quaternary sediment (광 여기 루미네센스를 이용한 신기 퇴적층의 연대측정)

  • 홍덕균;최정헌;한정희;최만식;정창식
    • The Journal of the Petrological Society of Korea
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    • v.10 no.3
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    • pp.202-211
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    • 2001
  • Luminescence is a physical phenomenon exhibited by many non-conducting, crystalline materials, such as quartz and feldspar. Within the crystals, energy absorbed from ionising radiation frees electrons to move through the crystal lattice and some are trapped at defects in the lattice. Observable luminescence is produced by electrons, released from traps by stimulation by absorption of light, which recombine with lattice defects which act as luminescence centers - optically stimulated luminescence (OSL). In a similar way to thermoluminescence(TL) dating, controlled measurement of the OSL signal can provide a means of determining the time since the last exposure of a layer of sediment to sunlight, the age of the sediment. However, whereas in the thermoluminescence dating of sediment only part of the latent thermoluminescence signal is bleached by sunlight as the sediment is deposited and allowance must be made during the laboratory measurements for the light insensitive component, optically induced luminescence dating has the advantage of working only with light sensitive traps in the crystal. Determination of the time since deposition of Quaternary sediment samples from the OSL of quartz grains using blue light was performed. A series of experiments and recent developments relating OSL dating are described, beginning by identifying the features which make OSL signals suitable for the development of dating method. Additionally, there are suggestions as to future research for obtaining reliable ages and a comment on current best practice on procedures, with the dating results of Quaternary sediment.

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A 3-D Measuring System of Thermoluminescence Spectra and Thermoluminescence of CaSO4 : Dy, P (열자극발광 스펙트럼의 3차원 측정 장치와 CaSO4 : Dy, P의 열자극발광)

  • Lee, Jung-Il;Moon, Jung-Hak;Kim, Douk-Hoon
    • Journal of Korean Ophthalmic Optics Society
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    • v.6 no.2
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    • pp.71-75
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    • 2001
  • In this paper, a three-dimensional measuring system of thermoluminescence(TL) spectra based on temperature, wavelength and luminescence intensity was introduced. The system was composed of a spectrometer, temperature control unit for thermal stimulation, photon detector and personal computer for control the entire system. Temperature control was achieved by using feedback to ensure a linear-rise in the sample temperature. Digital multimeter(KEITHLEY 195A) measures the electromotive force of Copper-Constantan thermocouple and then transmits the data to the computer through GPIB card. The computer converts this signal to temperature using electromotive force-temperature table in program, and then control the power supply through the D/A converter. The spectrometer(SPEX 1681) is controlled by CD-2A, which is controlled by the computer through RS-232 communication port. For measuring the luminescence intensity during the heating run, the electrometer(KEITHLEY 617) measures the anode current of photomultiplier tube(HAMAMATSU R928) and transmits the data to computer through the A/D converter. And, we measured and analyzed thermoluminescence of $CaSO_4$ : Dy, P using the system. The measuring range of thermoluminescence spectra was 300K-575K and 300~800 nm, $CaSO_4$ : Dy. P was fabricated by the Yamashita's method in Korea Atomic Energy Research Institute(KAERI) for radiation dosimeter. Thermoluminesce spectra of the $CaSO_4$ : Dy, P consist of two main peak at temperature of $205^{\circ}C$, wavelength 476 nm and 572 nm and with minor ones at 658 nm and 749 nm.

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Multistep Identification of γ-Irradiated Boiled-Dried Anchovies by Analysis of Thermoluminescence, Electron Spin Resonance, Hydrocarbon and 2-Alkylcyclobutanone (건멸치의 방사선 조사 확인을 위한 열발광, 전자스핀공명, Hydrocarbon 및 2-Alkylcyclobutanone의 다중분석)

  • 노정은;권중호
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.32 no.1
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    • pp.8-14
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    • 2003
  • Multistep detection was peformed to identify irradiated dried anchovy. In thermoluminescence (TL) analysis, non-irradiated samples represented a lower peak at about 28$0^{\circ}C$, but irradiated samples showed a higher peak at around 20$0^{\circ}C$. The normalization with a re-irradiation step at 1 kGy could verify the identification results. Electron spin resonance (ESR) spectroscopy for bones separated from irradiated anchovy revealed specific signals (g=2.002,1.998) derived from a hydroxyapatite radical, which intensities were in proportion to the irradiation doses and still detectable even after 6 months of storage at -2$0^{\circ}C$. Six kinds of hydrocarbons (HC) were observed in dried anchovy samples and 1,7-hexadecadiene and 1-hexadecene were only detected in irradiated anchovy at 1 kGy or more. Also among 3 kinds of radiation-induced 2-alkylcyclobutanones (2-ACB) observed, 2-dodecylcy-clobutanone and 2-tetradecylcyclobutanone were unique in irradiated anchovy. As a result, the concentration of radiation-induced HCs and 2-ACBs were dependent on the irradiation dose and detectable after 6 months of storage. However, TL and ESR analyses were found simpler than the other methods for identification of irradiated boiled-dried anchovy.

Analysis of the Detection Characteristics of Irradiated Dried Spices and Herbs by Photostimulated Luminescence (PSL) (광자극발광법(PSL)에 의한 방사선 조사 건조향신료의 검지 특성)

  • Park, Eun-Ryong;Kang, Hye-Soon;Ahn, Hyun-Joo;An, Kyung-A;Cho, Soo-Yeul;Kim, Hee-Yun;Kim, Dong-Sul;Kim, Do-Hoon;Kang, Chan-Soon
    • Korean Journal of Food Science and Technology
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    • v.42 no.2
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    • pp.136-141
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    • 2010
  • This study attempted to determine whether Photostimulated Luminescence (PSL) is applicable for the detection of post-irradiated foods by measuring the PSL photon counts of unirradiated and irradiated dried spices and herbs. A total of 19 dried spices and herbs was irradiated with a $^{60}Co$ $\gamma$-ray source at 1, 5 and 10 kGy followed by measurement of PSL photon. The photon counts of unirradiated samples below 700 correspond to negative. Fifteen samples irradiated over 1 kGy showed photon counts of more than 5,000, indicating irradiation treatment. Intermediate counts (photon count 700-5,000) were observed in irradiated white/black pepper, nutmeg and cinnamon bark at 10 kGy. These results suggest that it is possible to detect whether dried spices and herbs were irradiated by analyzing PSL, with the exception of white/black pepper, nutmeg and cinnamon bark. Irradiated white/black pepper, nutmeg and cinnamon bark containing low levels of minerals were not sensitive to PSL. Therefore, further investigation is sugguested to be performed by Thermoluminescence (TL) analysis or another validated or standardized method.

Monitoring on the Foods not Approved for Irradiation in Korea by PSL and TL Detection Method (광자극발광법과 열발광법을 이용한 국내 방사선 조사 허용 외 식품에 대한 실태 조사)

  • Cho, Joon-Il;Lee, Ji-Ae;Lee, Soon-Ho;Hwang, In-Gyun
    • Journal of Food Hygiene and Safety
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    • v.25 no.1
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    • pp.73-78
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    • 2010
  • This research was conducted to assess applicability of photostimulated luminescence (PSL) and Thermoluminescence (TL) methods for investigation of infant and young children products, nut, seasoned dried fish, spice, dried fruits, fruit & vegetable, grain and marine products, which are not approved for irradiation in Korea. PSL results show that the photon counts of non-irradiated samples were lower than 700, while those of irradiated samples were higher than 700. In TL measurement, TL ratio of irradiated samples were higher than 0.1 or ones can decrease below 0.1 whereas the temperature range of TL Glow curve was between $150{\sim}250^{\circ}C$. Monitoring result about 8 class of 325 not approved to irradiated foods, photon counts of samples were less than 700, and after re-irradiation TL Ratio ($TL_1/TL_2$) through re-irradiation step at 1 kGy were higher than 0.1 for the all samples. Therefore, these results suggested that PSL and TL measurements were useful detection methods for 8 class food products not approved to irradiation in Korea and all sample (325 cases) were not irradiated when we analysed by PSL and TL methods.

Detection Characteristics of TL, ESR and DNA Comet for Irradiated Peanuts by Origins (TL, ESR및 DNA Comet분석에 의한 원산지별 땅콩의 방사선 조사 검지 특성)

  • 이은영;정재영;조덕조;권중호
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.30 no.6
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    • pp.1076-1081
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    • 2001
  • Gamma-irradiated peanuts, Korean and Chinese origins, were investigated on detection properties by thermoluminescence (TL), electron spin resonance (ESR), and DNA comet assay (single cell gel electrophoresis). TL measurement showed that the non-irradiated sample revealed a glow curve with low intensity at about 25$0^{\circ}C$, while the irradiated samples showed higher intensity around at 18$0^{\circ}C$. TL ratio (TL$_1$/TL$_2$) of area for TL$_1$ glow curve to TL$_2$ was below 0.05 for the non-irradiated sample and 0.2 or more for the irradiated ones, thus identifying each other. ESR spectroscopy for the irradiated peanuts using outer skin showed negligible signals induced by irradiation, indicating ESR is little applicable to the detection of irradiated peanuts. In DNA comet assay, the non-sample had no or very short tails, whereas the irradiated samples revealed the cells with long tails. Significance in the increase of their lengths depending on irradiation dose (r=0.761/Korean, r=0.768/Chinese) was also found. There was no remarkable difference in detection properties by origins of samples in all determinations, It is concluded that TL analysis or DNA comet assay is suitable for detection of irradiated peanuts and a combined method is recommendable for enhancing the reliability of detection results.

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Detection Characteristics of Irradiated Aloe vera by the Analysis of PSL, TL and ESR (감마선 조사된 알로에 베라의 PSL, TL 및 ESR 검지 특성)

  • Kim Byeong-Keun;Lim Sang-Yong;Song Hyun-Pa;Yun Hye-Jeong;Kwon Joong-Ho;Kim Dong-Ho
    • Korean Journal of Food Preservation
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    • v.13 no.1
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    • pp.61-65
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    • 2006
  • Photostimulated luminescence (PSL), thermoluminescence(TL) and electron spin resonance (ESR) analyses were conducted to detect irradiation treatment of aloe vera powder, which was gamma-irradiated at 1, 3, 5 and 7 kGy. The non-irradiated aloe vera powder indicated below 700 of photon count in PSL, whereas, irradiated at 1 kGy and more, it showed more than 5,000 photon counts, indicating that it is feasible to detect the irradiation of aloe vera powder through PSL In the result of TL, from the minerals of the samples that were irradiated at more than 1 kGy, TL glow curve was able to be seen at around $150^{\circ}C$. As the quantity of irradiation goes up, the ratio of $TL_1\;and\;TL_2$ also increased in proportion to that of irradiation. In the result of ESR analysis, unspecific centeral ESR signal was could be seen. As the amount of irradiation on the samples increased to the level of $R^2=0.97$, the signal intensity also rose similarly. In conclusion, the PSL, TL and ESR exhibited the typical signals induced by irradiation treatment and were able to successfully detect all of the irradiated aloe vera powder. In addition, we found a positive correlation between the intensity of ESR and TL signals and irradiation doses.